lindows is the former name of the linux distribution Linspire. They changed the name due to legal reasons, but I can assure you it was not in any way actually based on windows code. It was/is simply an attempt at a similar system that is easy for windows users to migrate toward.
To the title of the thread, there are many other OS's out there, just not very heavily hyped.
There is of course BeOS, and BSD (sort of like unix) and freeBSD.... there are many others... search wikipedia for it, there is a rather complete list on there somewhere.